Regular:

Two-way time spreading and path-loss measurements were collected in water 100 m deep, off the coast of Nova Scotia. Data were collected at frequencies of 20-22 kHz, 27-29 kHz, and 35-37 kHz using... View More

Two-way time spreading and path-loss measurements were collected in water 100 m deep, off the coast of Nova Scotia. Data were collected at frequencies of 20-22 kHz, 27-29 kHz, and 35-37 kHz using linear FM pulses 0.160 s in duration. The source-receiver was an anchored, high-frequency active sonar, and the target was a free-drifting echo repeater. Sonar and target positions were recorded using a portable tracking range. In the paper, two-way time spreading and path loss measurements are compared with modeled estimates obtained using an enhanced version of the generic sonar model (GSM). The GSM estimates of time spreading due to multipath propagation compare favorably with the experimental data. The model indicates that the path loss for individual eigenrays was extremely sensitive to fluctuations in the sound-speed profile. This led to substantial variation in the model output depending on the choice of profile. In place of the model, an empirical estimate of path loss was computed from the data. We obtained a two-way spreading loss of 2[18.4log/sub 10/(R)] where R is the range from sonar to target. The data were also used to compute the standard deviation of the received echo intensity at each frequency. The standard deviation was computed two different ways. First it was computed using the peak echo level from each of the pulses at a given frequency. Then, it was computed from the total energy received from each of the pings. At all frequencies, the standard deviation was 1-2 dB lower when computed from the total received energy.

View Less

Related Documents

Modem ammunition-rocket system is a complicated multidisciplinary system. During its development, undetermined factors will bring many risks. This paper elaborates the importance of risk analysis approach to ammunition-rocket system development and analyses various methods of risk analysis and estim...

Face recognition based on few training samples is a challenging task. In daily applications, sufficient training samples may not be obtained and most of the gained training samples are in various illuminations and poses. Non-sufficient training samples could not effectively express various facial co...

The Spatial Only Processing Power Inversion (SOP-PI) algorithm is frequently used in Global Navigation Satellite System (GNSS) adaptive array receivers for interference mitigation because of its simplicity of implementation. This study investigates the effects of SOP-PI on receiver measurements for ...

The globally optimal recursive filtering problem is studied for a class of systems with random parameter matrices, stochastic nonlinearities, correlated noises and missing measurements. The stochastic nonlinearities are presented in the system model to reflect multiplicative random disturbances, and...

The path loss analysis model based on 5 rays in vacancy indoor environment is proposed. The relationship between multipath overlapping and the path loss is analyzed mathematically. Time-domain technique is introduced to compute reflection coefficient in a very short time interval. A 5 rays path loss...